Comparison of biochemical disease-free survival of patients with localized carcinoma of the prostate undergoing radical prostatectomy, transperineal ultrasound-guided radioactive seed implantation, or definitive external beam irradiation

Abstract

Purpose: This retrospective study compares the long-term biochemical disease-free survival for patients undergoing radical prostatectomy, transperineal ultrasound-guided 125Iodine implantation, or external beam irradiation alone in a tertiary referral community-based hospital. Methods and Materials: Five hundred forty patients were available for evaluation, which included: external beam, 132; 125I, 186; and radical prostatectomy, 222. For the 318 patients referred to the Department of Radiation Oncology, those with T3 disease underwent external beam irradiation while patients with T1 or T2 underwent 125I implantation or external beam irradiation as definitive treatment. No patient received androgen ablation. Patients undergoing irradiation were considered a biochemical failure if their PSA nadir was > 1 at 1 year or, if following a nadir PSA < 1, the patient subsequently experienced three consecutive rising PSA values obtained at a minimum 3-month interval. Patients undergoing prostatectomy were considered a biochemical failure if their postop PSA remained detectable > 0.2 ng/mL or if they had three consecutive increases in their PSA or an increase in their postoperative PSA warranting intervention with androgen ablation or external beam irradiation to the pelvis. Results: Patients were stratified by pretreatment risk groups predicting for post-treatment PSA recurrence. Patients were considered to be at a low or intermediate risk for recurrence if their clinical stage was T1c, T2a, T2b, pretreatment PSA level was ≤ 20, or their biopsy Gleason score was ≤ 6. Patients were considered to be at high risk for failure if they were clinically stage T2c, T3, PSA at diagnosis > 20, or Gleason score was ≥ 7. For 132 patients undergoing external beam irradiation, 28 of 37 low or intermediate risk obtained a 1 year nadir PSA of < 1 (76%) while 40% of high risk patients obtained nadir < 1. Of 186 patients undergoing 125I, 112 of 147 low or intermediate risk (76%) obtained a nadir PSA < 1. Twenty of 39 (51%) high risk obtained a nadir PSA < 1. Of the 222 patients undergoing prostatectomy, 83 of 88 (94%) low or intermediate risk had undetectable levels of PSA at 1 year. One hundred seventeen of 134 (86%) were high risk and had undetectable levels of PSA at 1 year. The biochemical disease-free survival for patients with low or intermediate risk at 5 years is approximately 70% with no significant difference between those patients treated with radical prostatectomy, external beam, or 125I. For those patients with high risk factors for recurrence, there is no significant difference between ultrasound-guided implant or external beam, but there is a significant improvement in biochemical disease-free survival with radical prostatectomy. Conclusion: For patients with low or intermediate risk disease, external beam, ultrasound-guided 125I, or a radical prostatectomy give comparable long-term biochemical disease-free survival. For patients with high risk disease, a radical prostatectomy provides a significantly improved biochemical disease-free survival. Our current protocols utilize androgen ablation in combination with conformal three-dimensional external beam irradiation or androgen ablation in conjunction with external beam irradiation and 103Pd seed implantation for patients at high risk for extra capsular disease. It is too early to determine if this combination therapy will give results comparable to radical prostatectomy. For patients who obtain a 1 year nadir PSA of < 1, the biochemical disease-free survival is durable with little risk of subsequent recurrence.